This invention relates generally to video cassette recorders (VCRs) and, specifically, to VCRs used in conjunction with television signal converters.
Most VCRs include user programmable ON/OFF and channel selection means for initiating and stopping recording of television signals on different television channel frequencies according to a user determined time schedule. Conventional VCRs may be programmed to record a plurality of television programs (events) extending over a substantial time period, generally limited by the number of events to be recorded and the length of the recording tape. Thus a user may program the VCR to automatically record one or more desired television programs on a number of different channels while the viewer is away from home or otherwise occupied for later, more convenient, viewing.
A large number of VCR users receive television signals over a cable in which the cable operator supplies his subscribers with locally receivable over-the-air television transmissions, in addition to other program signals, on a single cable installation. The subscriber receives a converter unit for translating the cable channel television signals to a single VHF channel frequency for viewing on the subscriber's television receiver. The converter unit may also incorporate a decoder for unscrambling selected channel signals which are available for an additional charge.
The converter unit is usually controllable from a remote point. Thus the subscriber is provided with a portable command signal transmitter for controlling operation of the converter unit. Generally the user may remotely turn the converter unit on and off, change the cable channel to which it is tuned and, in baseband systems, adjust and mute the volume in the audio of the received signal. The converter unit includes a command signal control unit for receiving the command signals and for performing the indicated functions.
A cable subscriber with a programmable VCR suffers a disadvantage in recording flexibility because the converter unit is not programmable to change channel tuning and only delivers a single cable channel to the input of the VCR. This cable channel is normally provided on VHF channel 3/4 and appears at the output of the converter unit. While the VCR has programmable channel selection means, enabling it to tune to any channel frequency, in practice it is always turned to VHF channel 3/4 because that is the only input signal available from the converter unit. Consequently, because the converter unit has no channel programming capability and only provides a single VHF channel output, the VCR has only that single channel frequency for an input and its programming capabilities, in terms of channel selection, are nullified.
The prior art as exemplified by German Pat. No. DT 26 12 260 A1 discloses a programmable command signal transmitter for a television receiver to turn the receiver on at a selected time, tune it to a desired channel and to turn the television receiver off at another time. The transmitter includes clock-controlled means for producing the appropriate command signals at the selected times. The art suggests nothing in the way of a solution to the dilemma of the cable subscriber with a VCR.